Challenges

Before giving the papers to the public, I would say a word to those
who may take an interest in them, and give them a little advice,
acquired by bitter experience. It is, to devote only such time as can
be spared from your legitimate business to the task, and if you can
spare no time, let the matter alone. Again, never, as I have done,
sacrifice your own and your family's interests to what may prove and
illusion; but, as I have already said, when your day's work is done,
and you are comfortably seated by your good fire, a short time devoted
to the subject can injure no one, and may bring its reward.

Challenge problems are optional, and meant to be somewhere between
quite difficult and nearly impossible. Work on them if you find it a
fun challenge and can do so without neglecting your responsibilities.

The value of a challenge is initially 100 points (equivalent to one
problem set). It may be reduced after a hint is provided.

The bonus points will be given for the first satisfactory
solution. Later solutions may receive some credit at my discretion,
but only if the significantly improve the first solution. You may
work in groups and consult external resources on challenge problems.
If N people work together on a challenge problem, each person
receives a bonus of value/sqrt(N).

Winners of a
challenge problem will also be expected to explain what they did to
the class.